【作者】 张博；

【导师】 陈定方；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 金属塑性成形过程模拟是实现短周期内，以较低成本设计出参数合理的模具，并制订最优的工艺参数，生产出高质量产品，它可以实时描述整个金属塑性成形过程。而要成功实现挤压成形工艺的过程模拟，依赖于许多因素，包括型材和模具尺寸、材料本构关系、摩擦、温度、挤压速度、加热长度等。成熟的仿真分析技术可以有效地降低企业的设计和生产成本，并获取许多常规试验手段无法测得的数据，从而增强企业研发新产品的能力和在市场上的竞争能力。作者对河南南阳红阳热冲压锻件厂进行了实地考察和调研，对该厂用热挤压方法生产的汽车半轴、支撑轴和挂车后桥进行虚拟仿真分析，验证了体积成形有限元方法的可行性，缩短了新产品的开发周期，降低成本，对实际工艺方案的设计起到了指导与借鉴作用，有助于企业综合竞争力的提升。本文分析了国内外的研究现状，论述了刚塑性有限元理论，借助刚塑性有限元理论研究热挤压的成形过程，进行了如下方面的研究工作：(1)分析了金属在高温下的流动应力、应变特性和对温度的敏感性，对高温金属材料的本构方程采用多元线性回归的方法进行数值拟合，并借助数值拟合公式预测20Cr在高温下的材料本构方程，为后续汽车后桥的有限元分析所使用。(2)利用二维有限元模拟软件Deform2D对汽车半轴的热挤压成形工艺过程进行计算机模拟，通过分析挤压过程中毛坯的预热温度、挤压速度、摩擦系数对变形力和锻件外形的影响，对挤压生产提出了一组优化工艺参数，与工厂现行加工工艺参数相同，验证了体积成形有限元法的真实性。(3)模拟汽车支撑轴管两步热挤压生产过程，并对汽车轴管热挤压的工艺方案和工艺参数进行分析和优化，得到理想的支撑轴外形。采用本文所述的两步成形热挤压工艺不仅可以节约材料，同时也可以节约工时，提高生产效率。(4)采用薄壁钢管毛坯来实现汽车后桥的成形，成形的不可预测性很大，在工厂的实际试验中，也经常出现金属堆料现象而导致挤压过程无法顺利进行。本文模拟、研究了汽车后桥桥壳的两步成形。分别研究了加热长度、摩擦和挤压速度等因素对汽车后桥成形的影响，采用单目标优化的方法，综合各因素的影响，得到了一组优化的工艺参数。对汽车后桥的挤压生产工艺起到指导作用。更多还原

【Abstract】 The metal plastic forming process simulation is the key technique which can design reasonable parameters of dies and draw better technical parameters at lower cost with short period, as well as describing the whole forming process. But achieving the numerical analysis successfully depends on various factors: including the shapes of the workpiece and tools, constructive relationship, the friction condition, temperature, velocity of the punch and length of calefaction for workpiece etc.The mature simulation technology can reduce designing and producing cost for the corporation effectively, achieving many data that the routine experiment methods can’t measure as well. So it can increase the development energy of the new products and the market competition of the corporation. In the paper, according to the field survey and research in the Hongyang thermal extrusion company in Nanyang , Henan provice, the virtual simulation method was used to research the extrusion process of the half axle, sustentation axle and the car behind bridge, which are produced with the extrusion method in the Hongyang factory. The feasibility of the volume figuration FEM was validated, which can also instruct the design of the fact technics scheme, and thereby decrease the research cycle of new products, reduce the cost and help to enhance the integration competition.In the paper, the current research condition in and abroad was analyzed; and the rigid plastic finite element theory was discussed. Based on the rigid plastic finite element theory, the summary main research works are done as follows:(1) The flow stress, strain characters and their sensitivity to temperature was analyzed. The multiple linear regression method was used to do the numerical fitting of the metal material constructive equation in high temperature. And the numerical fitting formula was used to forecast the constructive equation of the material 20Cr in high temperature, which was used in the following finite element analysis for the car behind bridge.(2) The software Deform2D was used to simulate the process of thermal extrusion of the car half-axle. And a group of optimized technological parameters were gained by analyzing the warm-up temperature, extrusion velocity and friction coefficient which was affected to distortion force and the shape of the product, which validate the facticity of bulk figuration FEM.(3)The two-step figuration technology was used to simulate the produce process of the car sustentation axle. The technics scheme and technics parameters of the car sustentation axle for hot extrusion were analyzed and optimized, and then achieved the perfect shape of the car sustentation axle. The two-step figuration technology related in the text can reduce materials, and also reduce work time and improve the manufacture efficiency greatly.(4)It is very uncertain to carry out the figuration of the car behind bridge with the thin steel tube. In the practical experiment of the factory, the phenomenon of metal material stacking usually appears too, which result in the extrusion process failing to carry through. In the paper, the two-step figuration of the car behind bridge was simulated and researched. The influence of the length heated up, friction coefficient and extrusion velocity was researched. Considering the influences of each factor, a group of optimized process parameters were achieved by using the single target optimizing method. And the parameters can instruct the actual hot extrusion of the car behind bridge.更多还原